The news of Jackson’s death comes amid growing concerns about football related injuries, especially concussions. In 2015, San Francisco 49ers star Chris Borland quit the sport at the age of 25, citing fears he would suffer long-term damage if he continued to play.

Earlier in March, for the first time ever, the National Football League acknowledged that head injuries acquired in the football field could lead to chronic traumatic encephalopathy, or CTE, a degenerative disease discovered in the brains of several former professional athletes.